/*
 * Copyright 2002-2021 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.transaction.annotation;

import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.ImportRuntimeHints;
import org.springframework.context.annotation.Role;
import org.springframework.transaction.config.TransactionManagementConfigUtils;
import org.springframework.transaction.interceptor.BeanFactoryTransactionAttributeSourceAdvisor;
import org.springframework.transaction.interceptor.TransactionAttributeSource;
import org.springframework.transaction.interceptor.TransactionInterceptor;

/**
 * {@code @Configuration} class that registers the Spring infrastructure beans
 * necessary to enable proxy-based annotation-driven transaction management.
 *
 * @author Chris Beams
 * @author Sebastien Deleuze
 * @since 3.1
 * @see EnableTransactionManagement
 * @see TransactionManagementConfigurationSelector
 */
@Configuration(proxyBeanMethods = false)
@Role(BeanDefinition.ROLE_INFRASTRUCTURE)
@ImportRuntimeHints(TransactionRuntimeHints.class)
public class ProxyTransactionManagementConfiguration extends AbstractTransactionManagementConfiguration {

	/**
	 * 配置通知
	 * ，关键是配置 TransactionAttributeSourcePointcut 切点，
	 * @param transactionAttributeSource 事务属性源，用于获取事务属性信息
	 * @param transactionInterceptor 事务拦截器，用于拦截事务方法并执行事务管理操作
	 * @return
	 */
	@Bean(name = TransactionManagementConfigUtils.TRANSACTION_ADVISOR_BEAN_NAME)
	@Role(BeanDefinition.ROLE_INFRASTRUCTURE)
	public BeanFactoryTransactionAttributeSourceAdvisor transactionAdvisor(
			TransactionAttributeSource transactionAttributeSource, TransactionInterceptor transactionInterceptor) {

		BeanFactoryTransactionAttributeSourceAdvisor advisor = new BeanFactoryTransactionAttributeSourceAdvisor();
		advisor.setTransactionAttributeSource(transactionAttributeSource);
		advisor.setAdvice(transactionInterceptor);
		if (this.enableTx != null) {
			advisor.setOrder(this.enableTx.<Integer>getNumber("order"));
		}
		return advisor;
	}

	/**
	 * 事务定义资源，使用 AnnotationTransactionAttributeSource 获取Class 或者 Method 上的 @Transactional 注解信息,
	 * 并封装成 TransactionAttribute 对象（TransactionAttribute 对象 包含 事务定义：事务隔离级别、事务传播行为）。
	 *
	 * AnnotationTransactionAttributeSource 内部初始化 TransactianlAnnotationParser 对象，用于解析 @Transactional 注解。
	 * @return
	 */
	@Bean
	@Role(BeanDefinition.ROLE_INFRASTRUCTURE)
	public TransactionAttributeSource transactionAttributeSource() {
		// Accept protected @Transactional methods on CGLIB proxies, as of 6.0.
		// 访问 protected  @Transactional 方法在 CGLIB 代理上，从6.0开始。
		return new AnnotationTransactionAttributeSource(false);
	}

	/**
	 *
	 * @param transactionAttributeSource
	 * @return
	 */
	@Bean
	@Role(BeanDefinition.ROLE_INFRASTRUCTURE)
	public TransactionInterceptor transactionInterceptor(TransactionAttributeSource transactionAttributeSource) {
		//1、创建事务拦截器
		TransactionInterceptor interceptor = new TransactionInterceptor();
		//2、设置事务属性源，执行代理方法时，会从事务属性源中获取事务定义信息，并根据事务定义信息执行相应的事务管理操作。
		interceptor.setTransactionAttributeSource(transactionAttributeSource);
		if (this.txManager != null) {
			interceptor.setTransactionManager(this.txManager);
		}
		return interceptor;
	}

}
